Jan Kundrát wrote:
> Steve Long wrote:
>>> Is [[:alpha:]] locale-safe?
>>>
>> Yes, all POSIX character classes listed here are:
>> http://www.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap07.html
>
> Thanks for a nice link. If I read section 7.3.1 correctly, [[:alpha:]]
> always contains those letters, but might contain more, depending on the
> locale. So it's probably very minor point, but as long as the script
> runs with user-provided locale, one should be explicit here. Or am I
> missing something here?
>
No, that's about the size of it-- if you you'd like to tie it to ASCII,
irrespective of locale, that's fair enough. It depends on what you're up to
(sorry, I don't have time to go digging through code to see what this
applies to) but in the /general/ case it's better to use locale-neutral
character-classes, since it makes scripts much more useful.
Setting LC_ALL=C temporarily is not a good idea, since it overrides
LC_CTYPE. The most common usage for that is for sort order; where that's
needed it's better to use LC_COLLATE. (man 7 locale)
Quick example showing why the double-bracket appears:
if [[ ${v:0:1} != [[:alpha:]_] || $v = *[^[:alnum:]_]* ]]; then
errMsg $"$v is not a valid identifier"
return 1
fi
Getting to know these is really helpful, imo, especially since they apply to
_all_ the utilities like tr, sed, grep, awk -- and ed ofc ;)
$"text" is for i18n in bash via gettext, akin to _"foo" in C. Can't say I've
used it yet, though :p
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